Stockholders' Equity - Additional Information (Detail) $ / shares in Units, $ in Millions			9 Months Ended		12 Months Ended
	Aug. 10, 2020 $ / shares shares	May 28, 2020	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) shares	Dec. 31, 2019 USD ($) $ / shares shares
Equity Class Of Treasury Stock [Line Items]
Reverse stock split, description		Reverse stock split – On May 28, 2020 following stockholder approval at our annual meeting, our board of directors approved a reverse stock split of our common stock at a ratio of 1-for-12, which was effective on June 1, 2020.
Reverse stock split, conversion ratio		12
Reclassification from common stock to additional paid-in capital | $			$ 3.3
Common stock par value | $ / shares			$ 0.01
Kronos Worldwide, Inc.
Equity Class Of Treasury Stock [Line Items]
Common stock, Repurchased			122,489	264,992
Stock repurchase, aggregate purchase price | $			$ 1.0	$ 3.0
Common stock , shares cancelled				110,303
Common stock, cancelled | $				$ 1.4
Shares available for purchase			1,600,000
Contran
Equity Class Of Treasury Stock [Line Items]
Preferred stock, par value | $ / shares	$ 0.01
Non-cumulative dividend on preferred stock	600.00%
Preferred stock returned to contribution agreement authorized designated	5,000
Series A Preferred Stock
Equity Class Of Treasury Stock [Line Items]
Preferred stock, shares outstanding					5,000
Preferred stock liquidation preference, per share | $ / shares					$ 133,466.75
Preferred stock, aggregate liquidation preference | $					$ 667.3
Preferred stock, par value | $ / shares					$ 0.01
Non-cumulative dividend on preferred stock					6.00%